Using the previously well characterized older cohort, we propose to determine the prevalence and predictors of osteoporosis at four sites in approximately 2400 men and women who are now aged 65 years or older. The original cohort consist of 1791 white men and 2091 women who were aged 50-79 at baseline examination in 1972-74 and who represent 82% of a geographically defined retirement community (Rancho Bernardo) is Southern California. Multiple possible predictors of osteoporosis already determined include: age, sex geographic origin of subject & parents, body mass index, blood pressure, diabetes, alcohol use, cigarette smoking, exercise, dietary intake, use of vitamins, minerals & medications, medical and surgical history, reproductive history and menopausal history, endogenous hormone levels (including insulin, adrenal and sex hormones) & sex hormone binding globulin, BUN, creatinine, liver function tests, uric acid, calcium (total and ionized), inorganic phosphorous, albumin, and globulin & urinalysis including microprotein, creatinine and calcium. Cohort followup is complete in 99.8%, with current addresses and contact persons identified for all survivors. Osteoporsis will be determine at the midshaft of the forearm and ultradistal wrist using single photon absorptiometry and at the spine and hip using dual photon absorptiometry. At the same visit we will update selected historical variables (e.g. diet, drugs, alcohol, smoking and exercise), ask a few new questions (e.g. family history of osteoporosis), remeasure height and weight, and obtain venous blood to establish a frozen serum bank. This prospective study will allow us to determine not only the prevalence of osteoporosis at four sites and the correlations of site specific osteoporosis with each other, but also the strength and independence of site-specific predictors of osteoporosis and whether any combination of modifiable attributes identifies those at greatest risk, for whom intervention may be appropriate. The frozen serum bank will allow us to test current or new hypotheses regarding osteoporosis using nested case-control studies as appropriate.